Powder supplying devices for powder coating installations are known. Such powder coating installations and the associated powder supplying devices are believed by the present inventors to be in need of careful cleaning when there is a change of powder (change from one type of powder to another type of powder), in particular when there is a change of color (change of powder of one color to powder having a different color), since just a few powder particles of the earlier type of powder may result in coating errors when coating with the new type of powder.